Method for ultra-dehydrating thickened or pasty biomass products, and equipment for implementing the method

ABSTRACT

The invention relates to a method for ultra-dehydrating thickened or pasty biomass products, in particular sludge from wastewater treatment plants, according to which the products, in particular products having a dryness of 4% to 25%, are subjected to the following steps: hydrothermal carbonization treatment, including pressurization ( 1, 2 ) and thermal conditioning ( 30 ) for a duration in a closed reactor ( 4 ); followed by dehydration of the products by a ram press ( 12 ), obtaining a dryness of more than 50%; the temperature of the product upstream from the ram press dehydration being regulated by cooling between 40° C. and 90° C., advantageously to around 70° C., in order to optimize the filterability in the piston press; the steps of the method being performed in a confined space making it possible to prevent the release of smells into the atmosphere.

PRIORITY

Priority is claimed as a national stage application, under 35 U.S.C. §371, to international patent application No. PCT/IB2014/061156, filedMay 2, 2014, which claims priority to French patent application 1354088,filed May 3, 2015. The disclosures of the aforementioned priorityapplications are incorporated herein by reference in their entirety.

The invention relates to a method for ultra-dehydrating thickened orpasty products forming a biomass, in particular treatment plant sludge.

The drying of such products is useful for a multi-sector recycling ofthe dried products, in particular for:

-   -   long-term storage without fermentation;    -   simple agricultural recycling that is acceptable to the        population, owing to a “sanitized” product;    -   an advantageous thermal recycling.

But the drying technology is accompanied by several impediments, inparticular:

-   -   its high energy consumption, mainly based on fossil energy;    -   the complexity of storing organic dried products that may        readily self-combust.

A sludge ultra-dehydrated to at least 50% dryness and preferably to 65%or more dryness has the advantages of:

-   -   absence of self-combustion during storage;    -   while retaining an advantageous thermal recycling;    -   sanitization of the product.

Dryers that currently exist, of direct or indirect type, may require,for the drying of the sludge, an energy of around 900-1100 kWh/TWE(tonne of water evaporated).

Systems of dryers with pre-evaporation of the sludge make it possible toobtain lower consumptions, of around 700-800 kWh/TWE.

Dryers that use heat pumps claim purely electrical consumptions of 300kWhe/TWE (kWhe=kilowatt-hour electrical), which amounts to an equivalentof around 900 kWh/TWE in terms of thermal energy.

Dryers that use mechanical steam compression claim thermal consumptionsof less than 300 kWhe/TWE, but mechanical steam compression technologyhas not displayed industrial implementability.

Furthermore, thermal conditioning of pasty products, and of sludge inparticular, has displayed an ability to substantially improve thedryness of a sludge by filter press dehydration. Thermal conditioningconsumes little energy, in particular when it is used on pasty andnon-liquid products since it does not carry out evaporation of water butonly a heating. There is therefore no noticeable heat loss.

One drawback of filter presses lies in the disassembling operation whichconsists in discharging the filter cake from the press. This filterpress operation generally requires a manual intervention, and theautomation thereof is difficult, if not impossible. The pressing anddisassembling operation of a conventional plate filter press isaccompanied by the release of odors into the atmosphere.

Moreover, the method of drying with thermal conditioning and filterpress is accompanied by problems of integration of the procedure forproducing ultra-dehydrated sludge regarding in particular:

-   -   the total energy consumption for producing a sludge        ultra-dehydrated to at least 50% dryness;    -   the management of the odors over the whole of the treatment        train;    -   the automation of the treatment train;    -   the ability to manage and store ultra-dehydrated sludge.

The objective of the invention is, above all, to propose a method thatmakes it possible to very substantially reduce, relative to thermaldrying, the total energy consumption for producing a sludgeultra-dehydrated to at least 50% dryness. The method must in additionmake it possible to: manage the odors, prevent them from leaking intothe atmosphere, automate the production and improve the ability tomanage and store ultra-dehydrated sludge.

The invention makes provision for the coupling of a hydrothermalcarbonization of dehydrated sludge, in particular having a dryness of 4%to 25%, with a ram press.

According to the invention, the method for ultra-dehydrating thickenedor pasty products, forming a biomass, in particular treatment plantsludge, is characterized in that the products, in particular having adryness of 4 to 25%, are subjected to the following steps:

-   -   hydrothermal carbonization treatment, comprising a        pressurization and a thermal conditioning for a residence time        in a closed reactor, followed by a decompression,    -   then dehydration of the products by a ram press, obtaining a        dryness of greater than 50%,    -   the temperature of the product upstream of the dehydration by        the ram press being regulated by cooling between 40 and 90° C.,        advantageously at around 70° C., in order to optimize the        filterability in the ram press, the steps of the method being        carried out in a confined space that makes it possible to        prevent the diffusion of odors into the atmosphere.

Preferably, for the hydrothermal carbonization treatment, thepressurization in the reactor is between 10 and 30 bar, preferably ofthe order of 20 bar, and the thermal conditioning is carried out byheating the products between 150 and 250° C. in the reactor.

The residence time of the products in the reactor is generally severalminutes, in particular between 15 and 200 minutes.

The method advantageously comprises a preheating of the product beforethe hydrothermal carbonization treatment.

The hydrothermal carbonization treatment may comprise the followingadditional steps:

-   -   an injection of reactant upstream of or into the reactor in        order to promote the reaction,    -   a heating in order to supplement the temperature in the reactor.

Preferably, the dehydration of the products by a ram press is carriedout through flexible drains that form filters, which are permeable tothe liquid that passes from the outside to the inside of the drains,whilst the solid materials are retained on the outside in order to bedischarged by disassembling.

The regulation of the temperature of the product upstream of thedehydration may be carried out with the aid of a chiller heat exchanger.

Advantageously, a conditioning of the product exiting the ram press iscarried out using a crusher or a grinder.

A dedicated cooling of the product exiting the ram press may be carriedout in order to reduce its temperature, preferably to a value below 40°C. The dedicated cooling may be of indirect type and be carried outunder vacuum.

A covered and deodorized store of product may be created between thehydrothermal carbonization treatment and the ram press. An automaticstart-up of the dehydration phase by the ram press may be carried out asa function of the level of product in the store.

Advantageously, a regulated deodorization is carried out during thedisassembling phase by a vacuum application enabling a bleeding of thegases or vapors that generate the odors. The non-condensable gases maybe subjected to a cooling. A use of the non-condensable gases ispossible in a boiler for thermal and odor-treatment purposes.

The invention also relates to an apparatus for ultra-dehydratingthickened or pasty products forming a biomass, in particular treatmentplant sludge, especially for the implementation of the method definedabove, characterized in that it comprises:

-   -   a unit for carrying out a hydrothermal carbonization treatment,        comprising a means for pressurizing the products, a means for        preheating these products, a closed reactor for a carbonization        residence time of the reheated products, and a means for        decompressing the products,    -   a device for cooling the products exiting the hydrothermal        carbonization treatment, in particular a chiller heat exchanger,    -   a ram press for dehydrating the products after hydrothermal        carbonization treatment, obtaining a dryness of greater than        50%,        the various components of the apparatus being in a confined        space that makes it possible to prevent the diffusion of odors        into the atmosphere and to manage these odors.

A covered and deodorized storage tank may be positioned between thehydrothermal carbonization treatment unit and the ram press.

Preferably, the ram press is provided in order to carry out a pressingof the products through flexible drains that form filters, which arepermeable to the liquid that passes from the outside to the inside ofthe drains under the effect of the pressure between two plates betweenwhich the drains extend, which drains deform when the plates approachone another, whilst the solid materials are retained on the outside ofthe drains in order to be discharged during the disassembling.

The apparatus may comprise a control assembly that makes it possible tocontrol the filterability of the product, the control assembly carryingout a measurement of the filtration time of the sludge at each pressingcarried out by a ram of the ram press, the combined filtration timesbeing compared to a reference value, and if the filtration duration,corresponding to the sum of the combined times, increases, the controlassembly gives a higher temperature set point for the sludge introducedinto the press.

Advantageously, the control assembly controls the amount of reactantinjected if the regulation of the temperature reaches its limit.

The ram press may have, upon disassembling, a slow opening sequencehaving a duration of at least 10 seconds in order to make it possible tochannel the odors.

A connection between the outlet of the ram press and the crusher or thegrinder may be produced in the form of a rigid hopper and/or a flexiblesheath forming a duct and enabling the channeling of the odors.

Preferably, all of the zones of the apparatus that may generate odors,in particular the store, the ram press and the crusher are placed undervacuum by a deodorizing ventilation system.

The apparatus, according to one variant, may comprise a direct feed ofthe ram press after a decompression, downstream of the hydrothermalcarbonization treatment unit.

Among the advantages provided by the invention, mention may be made of:

-   -   a reduced energy consumption,    -   an effective management of the odors,    -   a possibility of automatic operation,    -   suitable storage of the ultra-dehydrated sludge.

The invention consists, apart from the provisions set out above, of acertain number of other provisions which will be mentioned moreexplicitly below with respect to exemplary embodiments described withreference to the appended drawings, but which are in no way limiting.Regarding these drawings:

FIG. 1 is a diagram of an apparatus for dehydrating pasty products, inparticular treatment plant sludge, according to the invention,

FIG. 2 is a diagram of a variant of the apparatus from FIG. 1,

FIG. 3 is a schematic axial vertical cross section of a ram press duringoperation, and

FIG. 4 is an axial vertical cross section of the ram press during thedisassembling operation.

By referring to FIG. 1 of the drawings, it can be seen that the pastyproduct to be dehydrated, in particular the treatment plant sludge, isintroduced, as indicated by the arrow A, into a pressurizing assemblycomprising feeding equipment, formed by a screw 1, and a pumping meansformed by a pump 2. The product introduced has a dryness of between 4and 25%. The pumping assembly 1, 2 may be of the piston pump, gerotor,lobe pump or any other conventional pressurizing configuration type.

The product leaves the pump 2 under pressure, preferably between 10 and30 bar, advantageously of the order of 20 bar, in order to be preheatedin a heat exchanger 3.

The preheated product leaving the exchanger 3 is sent, via a duct 3 a,to a closed reactor 4 in order to remain therein for a residence time ofseveral minutes, in particular of 15 to 200 minutes, in order to undergoa hydrothermal carbonization therein. The products are heated in thereactor 4, at a temperature generally between 150-250° C., according toa conditioning, in particular a pressure of between 15 and 25 bar,advantageously of the order of 20 bar, which permits the catalysis. Alltypes of hydrothermal carbonization may be carried out.

A decompression of the products, leaving the reactor 4, is provided, inparticular with the aid of a decompression means, such as a valve 6,installed on the duct through which the products leaving the reactor 4pass.

The hydrothermal carbonization comprises, preferably, the followingadditional steps:

-   -   an injection 20 of reactant upstream of the reactor 4, as        illustrated in FIG. 1, or into this reactor, in order to promote        the hydrothermal carbonization reaction;    -   a heating means 30 in order to adjust the temperature in the        reactor 4;    -   a cooling means, in particular a heat exchanger 5, for cooling        the outgoing product before the decompression thereof by the        valve 6.

The heat exchanger 3 may be provided for a reheating of the product thatarrives, via the product leaving the reactor 4, as illustrated inFIG. 1. As a variant, the heat exchange may be provided via anintermediate fluid, in particular between the product that arrives andoil for the heating, or another conventional configuration for heatingproducts.

The reactor 4 may be in various shapes and may or may not be providedwith a stirrer, and/or baffles. The decompression may be provided by thevalve 6 or by a diaphragm or other mechanical means.

The means for heating the pasty products, in particular the sludge, formaintaining it at temperature, decompressing it, may assume anyconventional configuration.

The means 30 for heating the reactor 4 may be an indirect heating meanscomprising a shell surrounding the reactor 4 in order to form a chamberin which a hot fluid circulates, or a direct heating means consisting ofan injection of steam into the reactor 4.

The reactant(s) of the injection 20 for the hydrothermal carbonizationmay be selected from conventional reactants such as oxidant, acid, or acombination of the two.

The cooling of the outgoing product in the exchanger 5 may be carriedout by any type of conventional exchanger between outgoingproduct/cooling air, or outgoing product/cooling water.

The coolant of the exchanger 5 comes from a unit 50, via an inlet duct50 a provided with an adjustable opening valve 50 b controlled by acontrol assembly M. The coolant, reheated in the exchanger 5, returnsvia a duct 50 c to the unit 50 in order to be cooled therein or bereplaced therein by an already cold fluid.

The cooling provided by the exchanger 5 is regulated in order to enablean optimization of the dehydration. Indeed, if the product leaving theexchanger 5 is too hot, large amounts of steam are released, whereas ifthe product is too cold, the subsequent ultra-dehydratability iscompromised. The temperature of the product leaving the exchanger 5 isadjusted in order to optimize the filterability of the product duringthe step of dehydration by a ram press 12. Advantageously, thetemperature of the product leaving the exchanger 5 is between 40° C. and90° C., in particular around 70° C.

The hydrothermal carbonization unit, comprising the elements 1 to 6, 20and 30, is produced in a leaktight manner, so that gases or vaporscannot escape into the atmosphere. In the case of a rotary seal, asuction of the odors at this seal is put in place.

The products, in particular the sludge, conditioned by the hydro thermalcarbonization and cooled, are sent via a duct 5 a to a sealed storagetank, or chamber, 10 placed under a slight vacuum, by means of a draftdrawn by a duct 10 a connected to the tank 10, from a suction unit 40.The unit 40 also provides a treatment of the air before its release intothe atmosphere.

At least one temperature sensor 10-1 permanently provides thetemperature in the mass of products contained by the tank 10. Thistemperature is communicated to the control assembly M which adjusts theflow rate of coolant in the exchanger 5 in order to maintain a producttemperature, in the tank 10, that enables the best filterability duringthe following step, with minimum revaporization. Preferably, thetemperature of the product in the chamber 10 and at the outlet thereofinto a duct 10 b is maintained between 40° C. and 90° C., advantageouslysubstantially equal to 70° C.

Means for mixing the product in the storage tank 10 may be provided ifthe volume of this tank is such that the temperature measurement 10-1 atone point risks not being representative of the temperature of thevarious zones of the product. The number of measurement instruments, inparticular of temperature sensors, may be adapted as a function of thesize of the tank 10 and of the mass of products stored in order toenable a representativity of the overall temperature measurement. Thestorage tank 10 may also comprise a means E for measuring the level ofproduct. The result of the level measurement is sent to the controlassembly M for the automation of the treatment process:

-   -   in the case of a high level that exceeds a given high limit, the        stoppage of the operation of the thermal conditioning is        controlled, by stoppage of the pumping assembly 1, 2;    -   in the case of a low level, below a given low limit, the        operation of the units downstream of the tank 10, in particular        of a pump 11 and of a ram press 12, is stopped;    -   in case where the level in the tank 10 is between the low limit        and the high limit, the dehydration by the ram press 12 is        started up, as is the pump 11 that ensures the transfer of the        product between the outlet of the tank 10 and the inlet of the        ram press 12.

The sludge leaving the tank 10 via the duct 10 b is taken up by thehigh-pressure pump 11 which feeds the ram press 12.

As can be seen in FIG. 3, the filtration in the ram press 12 is carriedout in a closed cylinder 12 a which makes it possible to keep the odorsconfined throughout the pressing. At one end, located on the rightaccording to FIG. 3, the cylinder 12 a is sealed in a leaktight mannerby a plate 12 b, which may be moved apart therefrom in the axialdirection as illustrated in FIG. 4.

The product to be pressed is introduced into the cylinder 12 a via achannel 12 c provided at the center of the plate 12 b. At a distancefrom the plate 12 b, a ram 12 d subjected to a hydraulic or pneumaticpressure may slide in a leaktight manner into the cylinder 12 in orderto press the products introduced into the cylinder 12. Drains 12 e,formed by flexible sheaths made of material that is permeable to theliquid but impermeable with regard to the solids, are attached to acounterplate 12 f separate from the plate 12 b, but connected thereto.Each drain 12 e comprises an internal passage that opens into anassociated opening 12 g, provided in the counterplate 12 f. The openings12 g communicate with a chamber 12 h, between the counterplate 12 f andthe plate 12 b, which connects the liquid, essentially water, dischargedto the outside via a duct, not visible in FIG. 3.

At their other end, the drains 12 e are attached to a plate 12 iconnected to the ram 12 d from which it is separated in order to define,with the ram, a chamber 12 j which recovers the liquid that has passedthrough the drains 12 e. The drains are connected to openings 12 k thatpass through the plate 12 i and open into the chamber 12 j. The drains12 e extend substantially parallel to the geometric axis of the cylinder12 a when the ram is as far away as possible from the plate 12 b.

During the pressing, the ram 12 d carries out back-and-forth movementsin the direction of the axis of the cylinder 12 a, while the plate 12 bis held against the end of the cylinder 12 a. The flexible drains 12 edeform; the liquid expressed from the product passes through the wall ofthe drains 12 e and is discharged from the chamber 12 h. During thepressing operation, the ram 12 d and the plates 12 h, 12 f, 12 b may berotated about the geometric axis of the cylinder 12 a.

When the pressing is finished, the disassembling of the pressed sludge Btakes place as illustrated in FIG. 4. The plate 12 b moves in order toallow the opening of the chamber; the ram 12 d is brought to the end ofthe cylinder 12 a facing the plate 12 b. The pressed material B escapesvia gravity into the space thus freed while the drains 12 e take on aV-shape configuration. A rotational movement of the drains and of theplates to which they are attached may in addition be carried out duringthe disassembling. All these disassembling operations may easily berendered automatic.

The ram press 12, unlike other pressurized filtration devices of platefilter press or similar type, impart key advantages:

-   -   the filtration takes place in a sealed cylinder so that the        odors remain trapped throughout the pressing;    -   the management of the odors is facilitated since it is possible        to manage a slow opening of the cylinder in order to better        channel the odors;    -   the disassembling may be carried out automatically, in        particular owing to the movement of the drains 12 e;    -   the dehydrated product may be disassembled in the form of        pellets of relatively small size with the aid of a crusher or a        grinder 13 (FIG. 1), unlike the filter-press cakes that leave in        one piece and the size of which corresponds to that of the        plates of the filter press;    -   the disassembling is carried out in a controlled geographic zone        which may be isolated from the atmosphere by a shell, which        makes it possible to treat the residues in a controlled manner        and to prevent the propagation of the odors.

The filtered sludge B (FIG. 4), obtained at the end of pressing, leavescompact. In order to make it more easily transportable and storable, itis subjected to a crushing by falling into the crusher 13 (FIG. 1)suitable for dividing the filtered and ultra-dehydrated sludge intopellets or cords of reduced dimensions, in particular of the order of 10mm. The crusher 13 may comprise a receiving chute 13 a and two cylinders13 b, 13 c that rotate in opposite directions, provided with teeth orprotrusions that mesh, between which the dehydrated sludge undergoes afragmentation.

To prevent the diffusion of the odors into the atmosphere, a rigidhopper or a flexible sheath J may be provided in order to surround thecrusher 13 and the outlet of the press 12, and thus create leaktightnesswith respect to the atmosphere. The crusher 13 is also placed under aslight vacuum by a duct 13 d that connects the internal volume of thecrusher 13 to the suction unit 40.

A deodorizing system is installed above the ram press 12 via a duct 12.1connecting the internal volume of the press 12 at the suction unit 40.

The disassembling of the ram press 12 takes place in one go in awell-delimited zone. The odors that may escape at the outlet of thepress and in the crusher 13, in particular due to the fact of the heatstill remaining, are controlled. The opening of the press is controlledin order to enable, at the start of this opening, the escape of most ofthe odor-generating vapors which are sucked up by the duct 12.1 and,where appropriate, by the duct 13 d. The draft, providing the vacuum,from the unit 40 is strengthened at the moment of opening the press 12.

For the automation, the filtration time of the sludge at each pressingapplied by the ram 12 d is measured. The combined filtration times arecompared to a reference value. If the filtration duration correspondingto the sum of the combined times increases, the control assembly M,forming the control unit, gives a temperature set point for the sludgein the tank 10, and therefore for the sludge introduced into the press12, that is higher by one level that can be adjusted for a nextfiltration.

The injection 20 of reactant may be driven if the temperature 10-1 inthe tank 10 reaches a programmable high threshold. In this case, it isno longer desired to increase the temperature and the dose of reactantinjected is then played with in order to improve the filterability ofthe sludge in the press 12.

In order to ensure a storage of the dehydrated sludge leaving thecrusher 13 under good conditions, cooling equipment 14 is provided,after the crusher 13, in order to supplement the cooling of the productand store it at a temperature below 40° C., in particular at ambienttemperature.

The equipment 14 is also placed under vacuum with the aid of a duct 14 athat connects the internal volume of the cooling equipment 14 to thesuction unit 40. This vacuum application makes it possible to preventescapes of odors, even though they are lower at this level.

Preferably, the equipment 14 consists of a water-cooled screw, or twinscrew, which moves the dehydrated sludge from the outlet of the crusher13 to a storage container 15. The fluid used for cooling the dehydratedsludge circulates by coming from a cooling unit 60, and returningthereto in order to discharge the heat extracted.

Other cooling equipment could be used, in particular air-coolingdevices, such as perforated belts passed through by air, which air willthen be treated to eliminate the odors before release into theatmosphere.

The non-condensable gases recovered by the suction unit 40 are cooledand discharged via a duct 40 a. These non-condensable gases areadvantageously used as fuel in a boiler for thermal and odor-treatmentpurposes; they may otherwise be treated more completely by any suitablephysicochemical or biological means.

FIG. 2 illustrates an embodiment variant of the invention. The elementsthat are identical or similar to elements already described with respectto FIG. 1 are denoted by the same numerical references without theirdescription being repeated.

According to this variant, the elements from FIG. 1 formed by thestorage tank 10 and the high-pressure pump 11 are removed. The equipmentis thus reduced and the odors, the main production of which takes placeat the tank 10 from FIG. 1, may be better managed.

Instrumentation is added: a temperature-measuring probe 10-2 upstream ofthe exchanger 5, a valve 6 b downstream of the decompression valve 6 anda flow meter 10-3 downstream of the valve 6 b.

In this configuration, the operation of the thermal conditioning byhydrothermal carbonization, and that of the dehydration by ram press 12are concomitant. However, because of the fact that the cycle of the rampress 12 is not continuous and comprises filling phases, pressing phasesand emptying phases, there is no permanent flow in the thermalconditioning circuit. This can only lengthen the residence time of theproduct at high temperature and pressure, and leads to a bettertreatment.

In order to continue to regulate the temperature at the probe 10.1,which is an important point for the method of the invention, theoperation of the exchanger 5 is coupled to the flow rate measurement10-3. When the flow rate is zero, for example during the phase ofemptying the reactor 4, the circulation of the coolant in the exchanger5 is stopped.

Moreover, the flow rate for filling the press 12, corresponding to themeasured flow rate 10-3, is controlled by the decompression member 6. Inthis case, the member 6 is of reverse pump type, that can manage theregulation of the pressure and the stoppage of the emptying of theproduct, in particular of the sludge. The valve 6 b is installeddownstream of the decompression member 6, and makes it possible toensure the absence of flow leakage.

Finally, the initial pumping, provided by the pumping assembly 1, 2 isalso controlled in terms of flow rate by the ram press 12. Furthermore,within the context of this variant, it is possible to directly place adumpster under the ram press for dehydration without cooling.

The combination, according to the invention, of a thermal conditioningof pasty products via a hydrothermal carbonization treatment, with adehydration by a ram press makes it possible to obtain, with a minimalenergy consumption, dehydrated products that have a dryness of greaterthan 50%, in particular of the order of 65%, and to control the odorsthat are prevented from leaking into the atmosphere. The dimensions ofthe whole of the apparatus are reduced with respect to conventionalapparatuses carrying out an ultra-dehydration of sludge.

The invention claimed is:
 1. An apparatus for ultra-dehydratingthickened or pasty products forming a biomass, the apparatus comprising:a unit for carrying out a hydrothermal carbonization treatment,comprising a means for pressurizing the products, a means for preheatingthese products, a closed reactor for a carbonization residence time ofthe reheated products, and a means for decompressing the products, adevice for cooling the products exiting the hydrothermal carbonizationtreatment, in particular a chiller heat exchanger, a ram press fordehydrating the products after hydrothermal carbonization treatment andcooling, obtaining a dryness of greater than 50%, the various componentsof the apparatus being in a confined space that makes it possible toprevent the diffusion of odors into the atmosphere and to manage theseodors, wherein the ram press is provided in order to carry out apressing of the products through flexible drains that form filters,which are permeable to the liquid that passes from the outside to theinside of the drains under the effect of the pressure between two platesbetween which the drains extend, which drains deform when the platesapproach one another, whilst the solid materials are retained on theoutside of the drains in order to be discharged during thedisassembling.
 2. The apparatus as claimed in claim 1, wherein a coveredand deodorized storage tank is positioned between the hydrothermalcarbonization treatment unit and the ram press.
 3. The apparatus asclaimed in claim 1, further comprising a control assembly that makes itpossible to control the filterability of the product, the controlassembly carrying out a measurement of the filtration time of the sludgeat each pressing carried out by a ram of the ram press, the combinedfiltration times being compared to a reference value, and if thefiltration duration, corresponding to the sum of the combined times,increases, the control assembly gives a higher temperature set point forthe sludge introduced into the press.
 4. The apparatus as claimed inclaim 1, wherein the ram press has, upon disassembling, a slow openingsequence having a duration of at least 10 seconds in order to make itpossible to channel the odors.
 5. The apparatus as claimed in claim 1,wherein a connection between the outlet of the ram press and the crusheris produced in the form of a rigid hopper and/or a flexible sheathforming a duct enabling the channeling of the odors.
 6. Theultra-dehydrating apparatus as claimed in claim 1, further comprising adirect feed of the ram press after a decompression, downstream of thehydrothermal carbonization treatment unit.
 7. The apparatus as claimedin claim 3, wherein the control assembly controls the amount of reactantinjected if the regulation of the temperature reaches its limit.
 8. Theapparatus as claimed in claim 1, wherein all of the zones that maygenerate odors, in particular the store, the ram press and the crusherare placed under vacuum by a deodorizing ventilation system.